Ammonia is produced by the reaction of hydrogen and nitrogen. How many moles...?

write a balanced equation

3H2(g) + N2(g) ---------> 2NH3(g)

Now use the coefficients in front of each molecule to work out how many moles of each one you need from the starting moles you are given.

you can see
1 mole N2 needs 3 moles H2 to fully react
So 0.70 mole N2 needs (3 x 0.70) moles H2
= 2.10 moles H2 needed

2 moles NH3 form from 1 mole of N2
So 1 mole NH3 forms from 1/2 mole of N2
So 0.45 moles NH3 forms from (1/2 x 0.45) moles N2
= 0.23 moles N2 (2 sig figs)

3 moles H2 react to from 2 moles NH3
So 1 mole H2 will produce 2/3 moles NH3
Thus 1.6 mol H2 will form (2/3 x 1.6) moles NH3
= 1.067 moles NH3
= 1.1 moles NH3) (2 sig figs)